A Modified Iterative Packet Combining Scheme for Intersymbol Interference Channels

We study iterative combining (IC) technique for hybrid automatic repeat request (ARQ) scheme over inter-symbol interference (ISI) channels. By utilizing the extrinsic information transfer (EXIT) chart, we study the performance of the IC and find that the IC technique has a very good convergence behavior in the first little iteration, but it has a bad error floor, especially at the low signal-to-noise ratio (SNR). In this paper, we propose a modified IC scheme to overcome the shortcoming of the traditional IC. We study the receiver from another aspect in order to acquire a serial concatenation turbo-like scheme, and then we can combine the parallel (IC) and the serial concatenation turbo-like scheme together to propose a modified IC scheme. In this modified IC scheme, the EXIT chart as a balance switch between the two turbo-like schemes. It is shown that the proposed modified IC scheme provides excellent performance both analytically and through simulations without any computational complexity increase